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Updated: Jun 13, 2026

Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants
Published on: October 19, 2017
Production of technical grade phosphoric acid from incinerator sewage sludge ash (ISSA)
S Donatello1, D Tong, C R Cheeseman
1Department of Civil and Environmental Engineering, Imperial College London SW7 2AZ, UK.
Abstract:
The recovery of phosphorus from sewage sludge ash samples obtained from 7 operating sludge incinerators in the UK using a sulfuric acid washing procedure to produce a technical grade phosphoric acid product has been investigated. The influences of reaction time, sulfuric acid concentration, liquid to solid ratio and source of ISSA on P recovery have been examined. The optimised conditions were the minimum stoichiometric acid requirement, a reaction time of 120 min and a liquid to solid ratio of 20. Under these conditions, average recoveries of between 72% and 91% of total phosphorus were obtained. Product filtrate was purified by passing through a cation exchange column, concentrated to 80% H(3)PO(4) and compared with technical grade H(3)PO(4) specifications. The economics of phosphate recovery by this method are briefly discussed.
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